#!/bin/bash
function s1_generate_a_series_of_files(){
   for i in {1..100}; do 
       echo $i > /tmp/new_file$i
   done
}
function s2_list_4_files_in_long_format_about_account_and_group(){
   ls -l /etc/{passwd,shadow,group,gshadow} |sort -d
}
function s3_find_items_related_to_given_username(){
   username="$1"
   grep "^$username:" /etc/shadow
   grep "^$username:" /etc/passwd
}
function s4_find_items_related_to_given_group_name(){
   username="$1"
   grep "^$username:" /etc/gshadow
   grep "^$username:" /etc/group
}
function s5_create_groups_for_given_group_names(){
   groupadd rnd 
   groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required(){
   useradd -G rnd adam 
   useradd -G rnd bob 
   useradd -G itoperation calvin 
   useradd -G itoperation david 
   useradd -G rnd edward
}
function s7_change_users_shell(){
   usermod -s /usr/bin/sh adam 
   usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy(){
   passwd -n 10 -x 60 -w 10 adam
   passwd -n 10 -x 60 -w 10 bob
   passwd -n 10 -x 60 -w 10 david
   passwd -n 10 -x 60 -w 10 calvin
   passwd -n 10 -x 60 -w 10 edward
}
function s9_set_password_for_five_users(){
   local usernames=(adam bob calvin david edward)
   echo -e "${usernames[0]}:$1" | chpasswd
   echo -e "${usernames[1]}:$2" | chpasswd
   echo -e "${usernames[2]}:$3" | chpasswd
   echo -e "${usernames[3]}:$4" | chpasswd
   echo -e "${usernames[4]}:$5" | chpasswd
}
function s10_lock_bobs_password(){
   sudo usermod --lock bob
}
function s11_include_adam_into_wheel_group(){
   sudo usermod -a -G wheel adam
}
function s12_change_files_permission(){
   for (( i=3; i<=99; i+=3 )); do
        filename="/tmp/new_file${i}"
        if [ -f "$filename" ]; then
           chmod 640 "$filename"
        fi
   done
}
